Percutaneous needle-mediated interventions are widely used for diagnosing a large variety of diseases where biopsies of tissue are taken for tissue examination. In oncology, for example, biopsies of a pathological tissue region of interest are taken in order to examine whether this tissue is cancerous or not and, in case of a localized tumor, to determine whether the tumor is benign or malignant. A typical application scenario is mammographic visualization of cancerous tumors within a female patient's breast. In order to accurately diagnose and effectively treat the cancer, it may be necessary for a surgeon to excise a portion of the diseased tissue for microscopic examination and histological analysis. To make these interventions more reliable, representative feedback information indicative of the respective kind of tissue in front of the needle is required.
Traditionally, non-palpable breast lesions are excised with a wire as a guiding tool, which greatly facilitates image-guided needle biopsy and surgical resection by providing radiologists with a long wire marker having a small hook portion or spur at one end to be placed into the tissue under radiological control. Radiologic imaging techniques make it possible to display a localized focus of cancerous tissue deep within the internal organs of a patient. Imaging modalities such as X-ray, CT (computed tomography), PET-CT (positron emission tomography/computed tomography), MR (magnet resonance) and US (ultrasound) systems are used in the diagnostics of the diseases and for definition of the needle trajectory as well as for image-guided needle tracking.
Presuming that the guide wire has been accurately positioned, an image-guided needle biopsy based on X-ray, MRI, CT, sonography or hybrid radiography/MR imaging can be performed rapidly and accurately. Once the wire has been inserted into a tissue region of interest, an X-ray image may be taken to document the exact relationship of a wire's hook portion to the target lesion. The wire length thereby serves as a marker and guides the surgeon to a suspected lesion or node.
In general, each medical application requires a specific type of needle. Conventional biopsy needles as known from the prior art differ per clinical application in terms of their shapes, lengths and widths. For example, a biopsy needle used for carrying out soft tissue core biopsies in the neck, the head, the breast, the prostate, and the liver of a patient usually differs from brain biopsy needles, neuro puncture needles, epidural needles, fine aspiration needles for taking biopts from a soft tissue and needle electrodes for radiofrequency ablation of cancerous tissue in terms of its outer diameter and in terms of the length up to which the respective needle is inserted into a respective tissue region of interest. Conventionally, it is thus required to use an X-ray, CT, MR or ultrasound imaging modality for the determination of the lesion location, size, the patient's anatomy to be penetrated as well as for the definition of the needle type to be used.
Nowadays, so called photonic needles are increasingly used. A photonic needle is typically equipped with a light-guiding optical fiber integrated into a hollow cylindrical shaft in the interior of said needle for transferring light from a proximal end on which a generated light beam is incident to a distal end placed in a tissue region of interest around the tip of said needle in the interior of a patient's body, thereby providing an output light, assignable to the intensity of the generated light beam, which is needed for an excitation of a tissue sample to be minimally invasively examined, and transferring a collected beam of the reflected light from the tissue region of interest at the distal end to the proximal end of the needle.
Such a photonic needle may typically comprise a liquid-guiding cannula with a substantially tubular wall and an internal lumen having an open distal end similar to the cannula of a hypodermal syringe for providing a liquid given by a targeted contrast agent or dye fluorescent in the visible spectrum of light to the tip of the needle and applying this liquid to the pathological tissue region of interest so as to mark cancerous tissue anomalies.
In case of photonic needles, the type of tissue to be examined in front of the needle is identified by making use of spectroscopic measurements. To this end, a processing system used for interpreting these measurements is programmed for executing an algorithm which estimates different optical properties, such as e.g. the scattering coefficient and the absorption coefficient of different tissue chromophores (e.g. hemoglobin, oxygenated hemoglobin, water, fat, melanin, etc.).